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Metals
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Light Weight Alloys: Processing, Properties and Their Applications
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Light Weight Alloys: Processing, Properties and Their Applications

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Metal Casting, Forming and Heat Treatment".

Deadline for manuscript submissions: closed (28 February 2018) | Viewed by 82890

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Dr. Maurizio Vedani

E-Mail Website
Guest Editor
Department of Mechanical Engineering, Politecnico di Milano, Via Giuseppe La Masa 1, 20156 Milano, Italy
Interests: material science; metallurgy; additive manufacturing
Special Issues, Collections and Topics in MDPI journals
Dr. Riccardo Casati

E-Mail Website
Guest Editor
Department of Mechanical Engineering, Politecnico di Milano, Via Giuseppe La Masa 1, 20156 Milano, Italy
Interests: material science; metallurgy; additive manufacturing
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Light metallic alloys are continuously gaining growing interest for a wide number of applications owing to energy saving and environmental sustainability issues, as well as good processability for the easy shaping of parts and biocompatibility for medical applications (especially for Ti and Mg).

The aim of this Special Issue is to highlight recent innovations introduced in the fields of light alloys considering the perspectives of new materials and related processing routes and of new fields of applications and design strategies in these sectors.

Prof. Maurizio Vedani
Dr. Riccardo Casati
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Aluminum alloys
  • Titanium alloys
  • Magnesium alloys
  • Innovative Processing routes
  • Advanced design and applications

Published Papers (16 papers)

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Research

12 pages, 3423 KiB  
Article
Effects of Platform Pre-Heating and Thermal-Treatment Strategies on Properties of AlSi10Mg Alloy Processed by Selective Laser Melting
by Riccardo Casati, Milad Hamidi Nasab, Mauro Coduri, Valeria Tirelli and Maurizio Vedani
Metals 2018, 8(11), 954; https://doi.org/10.3390/met8110954 - 15 Nov 2018
Cited by 118 | Viewed by 8588
Abstract
The AlSi10Mg alloy was processed by selective laser melting using both hot- and cold-build platforms. The investigation was aimed at defining suitable platform pre-heating and post-process thermal treatment strategies, taking into consideration the peculiar microstructures generated. Microstructural analyses, differential scanning calorimetry, and high-resolution [...] Read more.
The AlSi10Mg alloy was processed by selective laser melting using both hot- and cold-build platforms. The investigation was aimed at defining suitable platform pre-heating and post-process thermal treatment strategies, taking into consideration the peculiar microstructures generated. Microstructural analyses, differential scanning calorimetry, and high-resolution diffraction from synchrotron radiation, showed that in the cold platform as-built condition, the amount of supersaturated Si was higher than in hot platform samples. The best hardness and tensile performance were achieved upon direct aging from cold platform-printed alloys. The hot platform strategy led to a loss in the aging response, since the long processing times spent at high temperature induced a substantial overaging effect, already in the as-built samples. Finally, the standard T6 temper consisting of post-process solution annealing followed by artificial aging, resulted in higher ductility but lower mechanical strength. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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17 pages, 3414 KiB  
Article
Springback Estimation in the Hydroforming Process of UNS A92024-T3 Aluminum Alloy by FEM Simulations
by Cristina Churiaque, Jose Maria Sánchez-Amaya, Francisco Caamaño, Juan Manuel Vazquez-Martinez and Javier Botana
Metals 2018, 8(6), 404; https://doi.org/10.3390/met8060404 - 01 Jun 2018
Cited by 7 | Viewed by 5173
Abstract
The production of metal parts manufactured through the hydroforming process is strongly affected by the difficulty in predicting the elastic recovery (springback) of the material. In addition, the formation of wrinkles and crack growth should be avoided. Manual cold work is widely employed [...] Read more.
The production of metal parts manufactured through the hydroforming process is strongly affected by the difficulty in predicting the elastic recovery (springback) of the material. In addition, the formation of wrinkles and crack growth should be avoided. Manual cold work is widely employed in industry to obtain the final shape of the manufactured parts. Therefore, an accurate springback estimation is of high interest to reduce the overall time of manufacturing and also to decrease the manual rectification stage. A working procedure based on finite element simulations (FEM) was developed to estimate the elastic recovery and predict the final morphology of UNS A92024-T3 aluminum alloy pieces after forming. Experimental results of real hydroformed parts were compared with the results obtained in simulations performed with PAM-STAMP software. The influence of different experimental parameters on the forming processes was also analyzed, such as the material properties, the rolling direction of sheet metal, or the hardening criteria employed to characterize the plastic region of the alloy. Results obtained in the present work show an excellent agreement between real and simulated tests, the maximum morphology deviations being less than the thickness of parts (2.5 mm). FEM simulations have become a suitable and mature tool that allows the prediction of the pieces springback, a precise material characterization being required to obtain reliable results. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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20 pages, 43987 KiB  
Article
High-Temperature Behavior of High-Pressure Diecast Alloys Based on the Al-Si-Cu System: The Role Played by Chemical Composition
by Elisabetta Gariboldi, Jannis Nicolas Lemke, Ludovica Rovatti, Oksana Baer, Giulio Timelli and Franco Bonollo
Metals 2018, 8(5), 348; https://doi.org/10.3390/met8050348 - 11 May 2018
Cited by 12 | Viewed by 5457
Abstract
Al-Si-Cu foundry alloys are widely applied in the form of high-pressure diecast components. They feature hypo- or nearly eutectic compositions, such as AlSi9Cu3(Fe), AlSi11Cu2(Fe), and AlSi12Cu1(Fe) alloys, which are used in the present study. Diecast specimens, with a thickness of 3 mm, were [...] Read more.
Al-Si-Cu foundry alloys are widely applied in the form of high-pressure diecast components. They feature hypo- or nearly eutectic compositions, such as AlSi9Cu3(Fe), AlSi11Cu2(Fe), and AlSi12Cu1(Fe) alloys, which are used in the present study. Diecast specimens, with a thickness of 3 mm, were used for tension tests. The short-term mechanical behavior was characterized at temperatures from 25 up to 450 °C. At temperatures above 200 °C, the tensile strength properties (YS and UTS) of the investigated alloys were severely affected by temperature, and less by chemical differences. Material hardness and ductility indexes better highlighted the differences in the mechanical behavior of these age-hardenable alloys and allowed us to relate them to the microstructure and its changes that took place at test temperatures. Thermodynamic calculations were found to be useful tools to predict phases formed during solidification, as well as those related to precipitation strengthening. By means of the performed comprehensive material characterization, deeper knowledge of the microstructural changes of Al-Si-Cu foundry alloys during short-term mechanical behavior was obtained. The gained knowledge can be used as input data for constitutive modeling of the investigated alloys. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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10 pages, 23532 KiB  
Article
Influence of Sludge Particles on the Fatigue Behavior of Al-Si-Cu Secondary Aluminium Casting Alloys
by Lorella Ceschini, Alessandro Morri, Stefania Toschi, Anton Bjurenstedt and Salem Seifeddine
Metals 2018, 8(4), 268; https://doi.org/10.3390/met8040268 - 14 Apr 2018
Cited by 12 | Viewed by 6709
Abstract
Al-Si-Cu alloys are the most widely used materials for high-pressure die casting processes. In such alloys, Fe content is generally high to avoid die soldering issues, but it is considered an impurity since it generates acicular intermetallics (β-Fe) which are detrimental to the [...] Read more.
Al-Si-Cu alloys are the most widely used materials for high-pressure die casting processes. In such alloys, Fe content is generally high to avoid die soldering issues, but it is considered an impurity since it generates acicular intermetallics (β-Fe) which are detrimental to the mechanical behavior of the alloys. Mn and Cr may act as modifiers, leading to the formation of other Fe-bearing particles which are characterized by less harmful morphologies, and which tend to settle on the bottom of furnaces and crucibles (usually referred to as sludge). This work is aimed at evaluating the influence of sludge intermetallics on the fatigue behavior of A380 Al-Si-Cu alloy. Four alloys were produced by adding different Fe, Mn and Cr contents to A380 alloy; samples were remelted by directional solidification equipment to obtain a fixed secondary dendrite arm spacing (SDAS) value (~10 μm), then subjected to hot isostatic pressing (HIP). Rotating bending fatigue tests showed that, at room temperature, sludge particles play a detrimental role on fatigue behavior of T6 alloys, diminishing fatigue strength. At elevated temperatures (200 °C) and after overaging, the influence of sludge is less relevant, probably due to a softening of the α-Al matrix and a reduction of stress concentration related to Fe-bearing intermetallics. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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996 KiB  
Article
A Unified Physical Model for Creep and Hot Working of Al-Mg Solid Solution Alloys
by Stefano Spigarelli and Chiara Paoletti
Metals 2018, 8(1), 9; https://doi.org/10.3390/met8010009 - 27 Dec 2017
Cited by 12 | Viewed by 3785
Abstract
The description of the dependence of steady-state creep rate on applied stress and temperature is almost invariably based on the Norton equation or on derived power-law relationships. In hot working, the Norton equation does not work, and is therefore usually replaced with the [...] Read more.
The description of the dependence of steady-state creep rate on applied stress and temperature is almost invariably based on the Norton equation or on derived power-law relationships. In hot working, the Norton equation does not work, and is therefore usually replaced with the Garofalo (sinh) equation. Both of these equations are phenomenological in nature and can be seldom unambiguously related to microstructural parameters, such as dislocation density, although early efforts in this sense led to the introduction of the “natural power law” with exponent 3. In an attempt to overcome this deficiency, a recent model with sound physical basis has been successfully used to describe the creep response of fcc metals, such as copper. The main advantage of this model is that it does not require any data fitting to predict the strain rate dependence on applied stress and temperature, which is a particularly attractive peculiarity when studying the hot workability of metals. Thus, the model, properly modified to take into account solid solution strengthening effects, has been here applied to the study of the creep and hot-working of simple Al-Mg single phase alloys. The model demonstrated an excellent accuracy in describing both creep and hot working regimes, still maintaining its most important feature, that is, it does not require any fitting of the experimental data. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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16698 KiB  
Article
Fabrication of an Ultra-Fine Grained Pure Titanium with High Strength and Good Ductility via ECAP plus Cold Rolling
by Haoran Wu, Jinghua Jiang, Huan Liu, Jiapeng Sun, Yanxia Gu, Ren Tang, Xincan Zhao and Aibin Ma
Metals 2017, 7(12), 563; https://doi.org/10.3390/met7120563 - 14 Dec 2017
Cited by 17 | Viewed by 5376
Abstract
Microstructure evolutions and mechanical properties of a commercially pure titanium (CP-Ti, grade 2) during multi-pass rotary-die equal-channel angular pressing (RD-ECAP) and cold rolling (CR) were systematically investigated in this work, to achieve comprehensive property for faster industrial applications. The obtained results showed that [...] Read more.
Microstructure evolutions and mechanical properties of a commercially pure titanium (CP-Ti, grade 2) during multi-pass rotary-die equal-channel angular pressing (RD-ECAP) and cold rolling (CR) were systematically investigated in this work, to achieve comprehensive property for faster industrial applications. The obtained results showed that the grain size of CP-Ti decreased from 80 μm of as-received stage to 500 nm and 310 nm after four passes and eight passes of ECAP, respectively. Moreover, abundant dislocations were observed in ECAP samples. After subsequent cold rolling, the grain size of ECAPed CP-Ti was further refined to 120 nm and 90 nm, suggesting a good refining effect by combination of ECAP and CR. XRD (X-ray diffractometer) analysis and TEM (transmission electron microscope) observations indicated that the dislocation density increased remarkably after subsequent CR processing. Room temperature tensile tests showed that CP-Ti after ECAP + CR exhibited the best combination of strength and ductility, with ultimate tensile strength and fracture strain reaching 920 MPa and 20%. The high strength of this deformed CP-Ti originated mainly from refined grains and high density of dislocations, while the good ductility could be attributed to the improved homogeneity of UFG (ultra-fine grained) microstructure. Thus, a high strength and ductility ultra-fine grained CP-Ti was successfully prepared via ECAP plus CR. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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7862 KiB  
Article
Study in Wire Feedability-Related Properties of Al-5Mg Solid Wire Electrodes Bearing Zr for High-Speed Train
by Bo Wang, Songbai Xue, Chaoli Ma, Jianxin Wang and Zhongqiang Lin
Metals 2017, 7(12), 520; https://doi.org/10.3390/met7120520 - 23 Nov 2017
Cited by 8 | Viewed by 4707
Abstract
This work offers an analysis of the wire feedability-related properties of Al-5Mg solid wire electrodes bearing Zr. Effects of Zr content on microstructures and mechanical properties of the Al-5Mg alloys were studied. Experimental results have demonstrated that α-Al dendrites of the as-cast Al-5Mg [...] Read more.
This work offers an analysis of the wire feedability-related properties of Al-5Mg solid wire electrodes bearing Zr. Effects of Zr content on microstructures and mechanical properties of the Al-5Mg alloys were studied. Experimental results have demonstrated that α-Al dendrites of the as-cast Al-5Mg alloy are refined, and the tensile strength, microhardness and roughness of the 1.2 mm wire electrode are improved with an appropriate addition of Zr. In addition, the tensile strength and elongation of the welded joints welded using Al-5Mg wire electrodes bearing Zr reach the maximum value when 0.12% Zr is added into the wire alloy. However, when excess Zr is added, α-Al phases of the wire alloy and welded joint are coarsened, and the mechanical properties are deteriorated. Moreover, the structure and principle of a novel apparatus, which can enhance the feedability of the wire electrode, are introduced and the apparatus can achieve the rough and fine adjustments of cast and helix of the wire electrode. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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9998 KiB  
Article
Optimization of Thermo-Mechanical Processing for Forging of Newly Developed Creep-Resistant Magnesium Alloy ABaX633
by Kamineni Pitcheswara Rao, Chalasani Dharmendra, Yellapregada Venkata Rama Krishna Prasad, Norbert Hort and Hajo Dieringa
Metals 2017, 7(11), 513; https://doi.org/10.3390/met7110513 - 21 Nov 2017
Cited by 4 | Viewed by 4756
Abstract
The compressive strength and creep resistance of cast Mg-6Al-3Ba-3Ca (ABaX633) alloy has been measured in the temperature range of 25 to 250 °C, and compared with that of its predecessor ABaX422. The alloy is stronger and more creep-resistant than ABaX422, and exhibits only [...] Read more.
The compressive strength and creep resistance of cast Mg-6Al-3Ba-3Ca (ABaX633) alloy has been measured in the temperature range of 25 to 250 °C, and compared with that of its predecessor ABaX422. The alloy is stronger and more creep-resistant than ABaX422, and exhibits only a small decrease of yield stress with temperature. The higher strength of ABaX633 is attributed to a larger volume fraction of intermetallic particles (Al, Mg)2Ca and Mg21Al3Ba2 in its microstructure. Hot deformation mechanisms in ABaX633 have been characterized by developing a processing map in the temperature and strain rate ranges of 300 to 500 °C and 0.0003 to 10 s−1. The processing map exhibits two workability domains in the temperature and strain rate ranges of: (1) 380 to 475 °C and 0.0003 to 0.003 s−1, and (2) 480–500 °C and 0.003 to 0.5 s−1. The apparent activation energy values estimated in the above two domains (204 and 216 kJ/mol) are higher than that for lattice self-diffusion of Mg, which is attributed to the large back-stress that is caused by the intermetallic particles. Optimum condition for bulk working is 500 °C and 0.01 s−1 at which hot workability will be maximum. Flow instability is exhibited at lower temperatures and higher strain rates, as well as at higher temperatures and higher strain rates. The predictions of the processing map on the workability domains, as well as the instability regimes are fully validated by the forging of a rib-web (cup) shaped component under optimized conditions. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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17069 KiB  
Article
Microstructure and Fatigue Properties of AlZn6Mg0.8Zr Alloy Subjected to Low-Temperature Thermomechanical Processing
by Aleksander Kowalski, Wojciech Ozgowicz, Adam Grajcar, Marzena Lech-Grega and Andrzej Kurek
Metals 2017, 7(10), 448; https://doi.org/10.3390/met7100448 - 21 Oct 2017
Cited by 9 | Viewed by 4778
Abstract
The paper presents results of the investigations on the effect of the low-temperature thermomechanical treatment on the microstructure of AlZn6Mg0.8Zr alloy (7003 alloy) and the relationships between microstructure and fatigue properties and fractography of fractured samples. Fatigue life has been determined in a [...] Read more.
The paper presents results of the investigations on the effect of the low-temperature thermomechanical treatment on the microstructure of AlZn6Mg0.8Zr alloy (7003 alloy) and the relationships between microstructure and fatigue properties and fractography of fractured samples. Fatigue life has been determined in a mechanical test at a simple state of loading under conditions of bending as well as torsion. The development of fatigue cracking has been described based on fractography investigations of the fractured samples making use of a scanning electron microscope (SEM). It was found that the factors determining the fatigue strength of the tested alloy are the microstructure as well as the type and size of the cyclic stresses. These factors determine the fractography of fatigue samples. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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14463 KiB  
Article
Characteristics of Resistance Spot Welded Ti6Al4V Titanium Alloy Sheets
by Xinge Zhang, Jiangshuai Zhang, Fei Chen, Zhaojun Yang and Jialong He
Metals 2017, 7(10), 424; https://doi.org/10.3390/met7100424 - 12 Oct 2017
Cited by 18 | Viewed by 6922
Abstract
Ti6Al4V titanium alloy is applied extensively in the aviation, aerospace, jet engine, and marine industries owing to its strength-to-weight ratio, excellent high-temperature properties and corrosion resistance. In order to extend the application range, investigations on welding characteristics of Ti6Al4V alloy using more welding [...] Read more.
Ti6Al4V titanium alloy is applied extensively in the aviation, aerospace, jet engine, and marine industries owing to its strength-to-weight ratio, excellent high-temperature properties and corrosion resistance. In order to extend the application range, investigations on welding characteristics of Ti6Al4V alloy using more welding methods are required. In the present study, Ti6Al4V alloy sheets were joined using resistance spot welding, and the weld nugget formation, mechanical properties (including tensile strength and hardness), and microstructure features of the resistance spot-welded joints were analyzed and evaluated. The visible indentations on the weld nugget surfaces caused by the electrode force and the surface expulsion were severe due to the high welding current. The weld nugget width at the sheets’ faying surface was mainly affected by the welding current and welding time, and the welded joint height at weld nugget center was chiefly associated with electrode force. The maximum tensile load of welded joint was up to 14.3 kN in the pullout failure mode. The hardness of the weld nugget was the highest because of the coarse acicular α′ structure, and the hardness of the heat-affected zone increased in comparison to the base metal due to the transformation of the β phase to some fine acicular α′ phase. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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2174 KiB  
Article
Structural and Mechanical Evaluation of a Nanocrystalline Al–5 wt %Si Alloy Produced by Mechanical Alloying
by Davood Dayani, Ali Shokuhfar, Mohammad Reza Vaezi, Seyed Reza Jafarpour Rezaei and Saman Hosseinpour
Metals 2017, 7(9), 332; https://doi.org/10.3390/met7090332 - 29 Aug 2017
Cited by 6 | Viewed by 3703
Abstract
High energy mechanical milling followed by hot-pressing consolidation has been used to produce nanostructured Al–5 wt %Si alloy. X-ray diffraction (XRD), scanning electron microscopy equipped with energy dispersive X-ray detector (SEM-EDX), Vickers hardness, and compression measurements were used to examine the effect of [...] Read more.
High energy mechanical milling followed by hot-pressing consolidation has been used to produce nanostructured Al–5 wt %Si alloy. X-ray diffraction (XRD), scanning electron microscopy equipped with energy dispersive X-ray detector (SEM-EDX), Vickers hardness, and compression measurements were used to examine the effect of milling duration on microstructure and mechanical properties of the nanostructured consolidated alloys. Crystallite sizes and lattice strains were determined by X-ray peak broadening analysis using the Williamson-Hall (W-H) method. Increasing the milling time reduced the crystallite size, and the minimum crystallite size of about 33 nm was achieved for both consolidated and powdered samples after 50 h of milling. Based on the SEM-EDX observations, the best distribution of silicon into Al matrix was obtained after 20 h of milling and remained unchanged afterwards. Hardness of both consolidated and powder samples increased with milling time, which can be attributed to the reduction of crystallite size and the better distribution of silicon in the aluminum matrix. Similarly, increased milling time increased the yield and compressive strengths of consolidated samples. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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7258 KiB  
Article
Hot Deformation Behavior of a Spray-Deposited Al-8.31Zn-2.07Mg-2.46Cu-0.12Zr Alloy
by Xiaofei Sheng, Qian Lei, Zhu Xiao and Mingpu Wang
Metals 2017, 7(8), 299; https://doi.org/10.3390/met7080299 - 04 Aug 2017
Cited by 8 | Viewed by 3718
Abstract
Metallic materials have a significant number of applications, among which Al alloys have drawn people’s attention due to their low density and high strength. High-strength Al-based alloys, such as 7XXX Al alloys, contain many alloying elements and with high concentration, whose microstructures present [...] Read more.
Metallic materials have a significant number of applications, among which Al alloys have drawn people’s attention due to their low density and high strength. High-strength Al-based alloys, such as 7XXX Al alloys, contain many alloying elements and with high concentration, whose microstructures present casting voids, segregation, dendrites, etc. In this work, a spray deposition method was employed to fabricate an Al-8.31Zn-2.07Mg-2.46Cu-0.12Zr (wt %) alloy with fine structure. The hot deformation behavior of the studied alloy was investigated using a Gleeble 1500 thermal simulator and electron microscopes. The microstructure evolution, variation in the properties, and precipitation behavior were systematically investigated to explore a short process producing an alloy with high property values. The results revealed that the MgZn2 particles were detected from inside the grain and grain boundary, while some Al3Zr particles were inside the grain. An Arrhenius equation was employed to describe the relationship between the flow stress and the strain rate, and the established constitutive equation was that: ε ˙ = [ sinh ( 0.017 σ ) ] 4.049 exp [ 19.14 − ( 129.9 / R T ) ] . An appropriate hot extrusion temperature was determined to be 460 °C. Hot deformation (460 °C by 60%) + age treatment (120 °C) was optimized to shorten the processing method for the as-spray-deposited alloy, after which considerable properties were approached. The high strength was mainly attributed to the grain boundary strengthening and the precipitation strengthening from the nanoscale MgZn2 and Al3Zr precipitates. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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4836 KiB  
Article
Effect of Fe-Content on the Mechanical Properties of Recycled Al Alloys during Hot Compression
by Hongzhou Lu, Zeran Hou, Mingtu Ma and Guimin Lu
Metals 2017, 7(7), 262; https://doi.org/10.3390/met7070262 - 10 Jul 2017
Cited by 14 | Viewed by 3903
Abstract
It is unavoidable that Fe impurities will be mixed into Al alloys during recycling of automotive aluminum parts, and the Fe content has a significant effect on the mechanical properties of the recycled Al alloys. In this work, hot compression tests of two [...] Read more.
It is unavoidable that Fe impurities will be mixed into Al alloys during recycling of automotive aluminum parts, and the Fe content has a significant effect on the mechanical properties of the recycled Al alloys. In this work, hot compression tests of two Fe-containing Al alloys were carried out at elevated temperatures within a wide strain rate range from 0.01 s−1 to 10 s−1. The effect of Fe content on the peak stress of the stress vs. strain curves, strain rate sensitivity and activation energy for dynamic recrystallization are analyzed. Results show that the recycled Al alloy containing 0.5 wt % Fe exhibits higher peak stresses and larger activation energy than the recycled Al alloy containing 0.1 wt % Fe, which results from the fact that there are more dispersed AlMgFeSi and/or AlFeSi precipitates in the recycled Al alloy containing 0.5 wt % Fe as confirmed by SEM observation and energy spectrum analysis. It is also shown that the Fe content has little effect on the strain rate sensitivity of the recycled Al alloys. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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8439 KiB  
Article
Characteristics of the Dynamic Recrystallization Behavior of Ti-45Al-8.5Nb-0.2W-0.2B-0.3Y Alloy during High Temperature Deformation
by Lin Xiang, Bin Tang, Xiangyi Xue, Hongchao Kou and Jinshan Li
Metals 2017, 7(7), 261; https://doi.org/10.3390/met7070261 - 08 Jul 2017
Cited by 13 | Viewed by 3517
Abstract
The dynamic recrystallization (DRX) behavior of Ti-45Al-8.5Nb-0.2W-0.2B-0.3Y (at %) alloy has been investigated through hot compression tests. The tests were executed at a temperature range of 1000–1200 °C and a strain rate range of 0.001–1 s−1 under a true strain of 0.9. [...] Read more.
The dynamic recrystallization (DRX) behavior of Ti-45Al-8.5Nb-0.2W-0.2B-0.3Y (at %) alloy has been investigated through hot compression tests. The tests were executed at a temperature range of 1000–1200 °C and a strain rate range of 0.001–1 s−1 under a true strain of 0.9. It was found that the α2 phase which is produced during heat treatment is reduced during hot compression due to thermo-mechanical coupling. The value of the activation energy is 506.38 KJ/mol. With the increase in deformation temperature and the decrease in strain rate, DRX is more likely to occur, as a result of sufficient time and energy for the DRX process. Furthermore, the volume fraction of high angle grain boundaries increases to 89.01% at a temperature of 1200 °C and the strain rate of 0.001 s−1, meaning completely dynamic recrystallization. In addition, DRX is related to the formation of twin boundaries. The volume fraction of twin boundaries rises to 16.93% at the same condition of completely dynamic recrystallization. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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36991 KiB  
Article
Effect of Anode Pulse-Width on the Microstructure and Wear Resistance of Microarc Oxidation Coatings
by Zhen-Wei Li and Shi-Chun Di
Metals 2017, 7(7), 243; https://doi.org/10.3390/met7070243 - 30 Jun 2017
Cited by 5 | Viewed by 3663
Abstract
Microarc oxidation (MAO) coatings were prepared on 2024-T4 aluminum alloys using a pulsed bipolar power supply at different anode pulse-widths. After the MAO coatings were formed, the micropores and microcracks on the surface of the MAO coatings were filled with Fluorinated ethylene propylene [...] Read more.
Microarc oxidation (MAO) coatings were prepared on 2024-T4 aluminum alloys using a pulsed bipolar power supply at different anode pulse-widths. After the MAO coatings were formed, the micropores and microcracks on the surface of the MAO coatings were filled with Fluorinated ethylene propylene (FEP) dispersion for preparing MAO self-lubricating composite coatings containing FEP. The effect of the anode pulse-width on the microstructure and wear resistance of the microarc oxidation coatings was investigated. The wear resistance of the microarc oxidation self-lubricating composite coatings was analyzed. The results revealed that the MAO self-lubricating composite coatings integrated the advantages of wear resistance of the MAO ceramic coatings and a low friction coefficient of FEP. Compared to the MAO coatings, the microarc oxidation self-lubricating composite coatings exhibited a lower friction coefficient and lower wear rates. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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3552 KiB  
Article
Influence of Temperature-Dependent Properties of Aluminum Alloy on Evolution of Plastic Strain and Residual Stress during Quenching Process
by Yuxun Zhang, Youping Yi, Shiquan Huang and Hailin He
Metals 2017, 7(6), 228; https://doi.org/10.3390/met7060228 - 21 Jun 2017
Cited by 23 | Viewed by 6598
Abstract
To lessen quenching residual stresses in aluminum alloy components, theory analysis, quenching experiments, and numerical simulation were applied to investigate the influence of temperature-dependent material properties on the evolution of plastic strain and stress in the forged 2A14 aluminum alloy components during quenching [...] Read more.
To lessen quenching residual stresses in aluminum alloy components, theory analysis, quenching experiments, and numerical simulation were applied to investigate the influence of temperature-dependent material properties on the evolution of plastic strain and stress in the forged 2A14 aluminum alloy components during quenching process. The results show that the thermal expansion coefficients, yield strengths, and elastic moduli played key roles in determining the magnitude of plastic strains. To produce a certain plastic strain, the temperature difference increased with decreasing temperature. It means that the cooling rates at high temperatures play an important role in determining residual stresses. Only reducing the cooling rate at low temperatures does not reduce residual stresses. An optimized quenching process can minimize the residual stresses and guarantee superior mechanical properties. In the quenching process, the cooling rates were low at temperatures above 450 °C and were high at temperatures below 400 °C. Full article
(This article belongs to the Special Issue Light Weight Alloys: Processing, Properties and Their Applications)
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